The principal objectives of this project are to purify and characterize proteins (enzymes) from human plasma and the rabbit macrophage which have been implicated in the detoxification of bacterial endotoxins. A major effort also will be made to isolate and characterize enzymatic endproducts from these reactions. Purifications of the detoxifying proteins and major endproducts of detoxification will be achieved by standard biochemical procedures, including column chromatography, gel electrophoresis as well as immunochemical techniques. These studies may lead to a better understanding of an important host defense mechanism. In view of the current clinical problems associated with gram negative sepsis, knowledge gained from the identification and function of detoxifying enzymes may eventually lead to more effective procedures for the treatment and prevention of endotoxic shock.